This invention relates generally to parts, such as turbine blades, that have internal cavities and, more particularly to a method and apparatus for cleaning the internal cavities thereof.
In the manufacture or repair of turbine blades of the type used in the high pressure turbine of a gas turbine engine, the internal cavities of the blade are left with a residue of undesirable foreign material such as salts, silicone and silk, which must be removed from the internal cavities in order to obtain proper performance therefrom. In addition, the foreign material can collect in corners or other such locations within the internal cavities. The usual method of cleaning these internal surfaces is to conduct an autoclave or ultrasonic cleaning operation, followed by a flushing out of the cavities by the use of a high pressure washing process.
The flushing process is commonly accomplished by using one or more probes to introduce a high pressure flow of a liquid such as water into one or more of the cavities in order to wash out the undesirable residue.
The apparatus for positioning the probes with respect to the blade cavity has generally been of two types. The one that has been used following the autoclave process was that of a single blade being flushed by a pair of probes simultaneously registering with their respective cavities, after which the probes were retracted and then indexed to the next blade for the same process.
Another prior art process that has been used after ultrasonic cleaning is that of a fixture having a pair of extended probes that separately register with individual cavities of two different blades. After the respective cavities have been cleaned, the fixture is retracted and then indexed to adjacent cavities in the same respective blades.